The N1 union said 84 percent of its members had backed the strike, with a "historic" turnout of 2,330 of 2,500 people eligible to vote.

"We hope that this overwhelming desire to reject the company's offer... will convince the company of the need to show a willingness to build an accord that recognizes our rights," N1 said in a statement.

The union is calling for a five percent salary increase and a conflict termination bonus of four percent of dividends received by shareholders last year, or about $34,000 per worker.

BHP hasn't commented on the strike action.

The company increased its initial offer of 13.5 million Chilean pesos to 15 million ($23,000) per worker as a bonus for ending the negotiations, which had dragged on for weeks.

BHP, a multinational mining, metals and petroleum company that posted revenues of $38 billion and $5.9 billion in bottom line profit last year, has the right to request mediation, which could last 10 days.

If that fails, workers would go on strike.

Last year, Escondida miners went on strike for 44 days, provoking a 39 percent drop in production over the first half of the year, costing the company $740 million.

Some five percent of the world's copper is produced at the mine, one of the most profitable in the world.

It earned almost $1.2 million in revenues last year, a 20 percent increase on the previous year, and that despite the lengthy industrial action.

That hurt the local economy, though, in a country that produces almost a third of the world's copper, around 5.6 million tons, fuelled largely by China's insatiable appetite for the red metal.

The government had pleaded with miners on Wednesday to be "realistic."

"Strike action is a legitimate tool, but without a doubt we hope the problems can be resolved without resorting to a strike," Finance Minister Felipe Larrain said.

The Escondida mine is located in the world's driest desert, the Atacama in northern Chile, at more than 3,000 meters (10,000 feet) in altitude.

It's the same area where eight years ago 33 men were trapped 700 meters underground for 69 days following a cave-in at the Copiapo mine.

Earlier this week, at yet another mine in Chuquicamata, run by the state-owned Codelco company, workers briefly went on strike to demand the reinstatement of sacked colleagues.